User Guide

CALIBRATION

The controller is factory calibrated for mV and temperature

inputs as well as for the analog outputs.

The user should periodically calibrate the instrument. For great-

est accuracy, it is recommended that the instrument is calibrated

frequently.

It is possible to standardize the electrode with only one buffer,

preferably close to the expected sample value (one-point cali-

bration), but it is always good practice to calibrate in at least

2 points.

pH CALIBRATION (for pH 502 Series only)

The pH controller can be calibrated through a one-point,

two-point or three-point calibration. You do not need to en-

ter the method chosen, simply exit the

calibration mode, by pressing CAL,

when the desired number of points has

been calibrated.

The calibration points for pH 502 are

pH 4.01, pH 7.01 and pH 10.01 (at

25°C). The sequence proposed by the

controller is pH 7.01, pH 4.01, pH

10.01. However, the user can change

this sequence by means of the  and

 keys.

The electrode must be kept hydrated at all times and defi-

nitely prior to calibration. The temperature probe should also

be connected to the process meter. The meters are equipped

with a stability indicator. The user is also guided with indica-

tions on the display during the calibration procedure.

Initial Preparation

Pour small quantities of pH 7.01 (HI 7007) and pH 4.01

(HI 7004) and/or pH 10.01 (HI 7010) solutions into indi-

vidual beakers. If possible, use plastic beakers to minimize

any EMC interference.

HI 7007

HI 7004